// Oldham, Jeffrey D.
// 2000 Jan 04
// CS1321

// CS1321 Homework 1: Compute Sales Tax 

// Compute the sales tax for a given list of item prices in a given state.
// Command line arguments:
// 1. name of file containing states and sales tax rates
// 2. name of the state for the transaction
// 3. any number of item prices written as decimals with two decimal points

// Revisions:
// 2000Jan24: round() does not work correctly for negative numbers.
// Since setprecision() apparently works correctly, we need not worry
// any more.

#include <iostream>
#include <iomanip>
#include <stdlib.h>		// has strtod()
#include <string>
#include <fstream>

// Find the sales tax rate in the file corresponding to the state.
// Return a negative number if no rate is found.
double salesTaxRate(const string & filename, const string & state);

// I cannot find the library containing round() so I will write my own
// function. :(
// 2000Jan24: does not work correctly for negative numbers :(
double round(const double d) {
  return static_cast<int>(d + 0.5);
}

int main(int argc, char *argv[])
{
  if (argc < 3) {
    cerr << argv[0] << ": sales-tax-file state item-prices ...\n";
    exit(EXIT_FAILURE);		// I found this EXIT_FAILURE macro recently.
  }

  // Determine the sales tax rate.
  double rate;
  if ((rate = salesTaxRate(argv[1], argv[2])) < 0) {
    cerr << argv[0] << ": sales tax rate for " << argv[2]
	 << " not found\n";
    exit(EXIT_FAILURE);
  }

  // Determine the total item cost.
  double cost = 0.0;
  for (int i = 3; i < argc; ++i)
    cost += strtod(argv[i], static_cast<char **>(0));

  // Print the answer.
  cout.setf(std::ios::fixed);
  // JDO 2000Jan24:  cout << setprecision(2) << round(cost * rate) / 100.0 << endl;
  cout << setprecision(2) << cost * rate / 100.0 << endl;

  return 0;
}


// Find the sales tax rate in the file corresponding to the state.
// Return a negative number if no rate is found.
double salesTaxRate(const string & filename, const string & state) {
  ifstream in(filename.c_str());
  if (!in) {
    cerr << "Failed to open " << filename << ".\n";
    exit(EXIT_FAILURE);
  }
  string abbrev;
  double rate;
  while ((in >> abbrev >> rate) && (abbrev != state))
    ;

  in.close();
  if (abbrev == state)
    return rate;
  else
    return -1.0;
}